260 R. T. HILL — PELE AND THE WINDWARD ARCHIPELAGO 



geology, all of the Windward islands appear to be members of a kindred 

 archipelago. This is not the case. In fact, however, they present sev- 

 eral distinct geologic and physiographic subtypes. The Virgin islands 

 at the north are Antillean, while Tobago and Trinidad are South Amer- 

 ican in natural relations. 



From the remaining Windward islands — lying between the Anegada 

 passage and Tobago — we must again detach Barbados,* as isolated from 

 the chain in geologic peculiarity as it is geographically. 



The remaining islands, the main Windward group, are geographically 

 divisible into two parallel north-and-south belts extending the length 

 of the archipelago. The eastern belt, composed of sedimentary rocks, 

 includes Sombrero, Dog, Anguilla, Saint Martin, Saint Bartholomew, 

 Barbuda, Antigua, the Grande Terre of Guadeloupe, Marie Galante, and 

 Desirade. 



The inner belt facing the Caribbean — the Caribbee islands proper — 

 includes Saba, Saint Eustatius, Saint Christopher, Nevis, Montserrat, 

 Basse Terre, Guadeloupe, Dominica, Martinique, Saint Lucia, Saint Vin- 

 cent, the Grenadines, and Grenada. These, attaining heights approxi- 

 mating 5,000 feet in some of the islands mentioned, with Saba and Saint 

 Eustatius at the north, which rise 2,820 and 1,950 feet respectively, and 

 the Grenadines to the south, comprise the newest and highest summits 

 of the Windward group. 



CONFIGURATION OF THE ISLANDS 



(See map, plate 43.) 



Land heights and oceanic depths. — A proper conception of the origin and 

 relation of these islands likewise requires a study not only of the land 

 areas, but of the configuration of the adjacent slopes and bottoms. In 

 interpreting their physiography the height of the islands should be con- 

 sidered from the ocean floor rather than sealevel, above which only one- 

 third of the total relief is visible. 



* The island of Barbados, which thus rises from an independent submarine ridge parallel to the 

 main Caribbee chain and to the eastward thereof, and its geological structure and composition 

 present a singular dissimilarity from that of all the other Windward islands. Its fundamental 

 beds, sands, and clays, called the Scotland beds, are intensely folded sediments, derived from 

 the same unknown preexisting land and resembling similar rocks of Trinidad and Jamaica. 

 These beds also show strong lines of folding, which must have taken place before Pliocene time. 

 This fundamental formation again is veneered by the purest type of ocean formation known to 

 occur anywhere, namely, radiolarian earths, which testify that the island was submerged to a 

 great depth, veneered with radiolarian formation, and reelevated again. Still later, in Pleisto- 

 cene and recent times, the island has gradually emerged from the sea coated with this veneering 

 of coral reefs, these later movements probably being synchronous with those of the main Caribbee 

 ridge. In its earlier Eocene history Barbados was South American and probably a peninsulate 

 from the mainland. In its later Pleistocene and recent history it has participated in the oscilla- 

 tions of the Windward islands. (See map, plate 43.) 



